2011 International Year of Forests – More invasive threats to our forests

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Columnar Cacti with the symptoms as described in the article. Large cacti of more than one hundred years old die suddenly.

It’s weird how little control there is on the import of plants, garden soil, building materials and other products in which pests can hide. Whether we talk about seeds from plants that do not belong here, like the Bellisima and Palu di Lechi described in the previous article, or other organisms, the damage to nature can amount to such levels that no matter how many times we pronounce the words ‘nos naturalesa’, at one point there simply will be nothing left. Plant diseases carried by plants from abroad, of which is thought that no injury to the local flora is possible, might develop into a severely destructive pest because native plants have no effective defenses against such a threat from the outside.

Danger of eradication!

Because Island populations, the number of animals or plants of one species, are relatively small due to the small size of the island, a carelessly imported viral or bacterial disease can completely eradicate an entire species. Until a few years ago, for example, we’d never heard of leaf cutter ants on Curacao. Discovery Channel broadcasted beautiful documentaries about these particular ants that ‘cut off’ pieces of leaves with great precision for transportation back to their nest. Transportation takes place in a long, well organized line, and they carry the leaf pieces like an umbrella on their backs. At this moment in time these ants are also present on our island. In a wet, rainforest-type of ecology the balance between these animals and the plants stays intact. On an island like Curacao, where plants and trees are in a constant climate-induced struggle for survival, especially in the dry season, these gardening ants might impose a fatal blow from which the plants can not recover, with all its consequences. How these ants entered the Island is not entirely clear. The suspicions point to imported potted plants, and after the first emission of new queens the species established several nests. Many gardeners will pull hair from their heads in frustration when discovering that for the umpteenth time their precious Kayena has been ransacked.

The Red Fire ant, one of the worlds most dangerous ant species.

Fiery threat

But experts do not fear these ants the most. That ‘honor’ goes to the so called Red Fire Ant. These insects live in large nests and are destructive to gigantic proportions. Within a few hours they can totally eradicate one square kilometer of forest, including all flora and fauna elements. The animals are black to reddish in color, beautifully shiny in appearance, and  extremely dangerous, even for people. Because they always attack in massive groups a victim has no chance of escape. There are no confirmed sightings on the Island yet, but it’s a matter of time before these animals will set foot on Dushi Korsou. That is, if nothing is done to control the import of stuff they might hide in.

Columnar Cactus Problem

Sometimes it is not clear whether a problem with local plants and trees is due to an invasive species. Anyone who in recent years has looked a little better at the picturesque pillar cacti on the island has probably noticed that all is not well with the Kadushi’s. The cactus population has a hard time and in different places mortality of large majestic cacti can be observed. Personal observations have shown that we are dealing with a fixed die-off pattern. Around a ‘wound’ inflicted to a branch, the tissue begins to rot. It slowly spreads to the whole branch and from there to the rest of the cactus. The plant actually rots from the inside out and turns into a stinking pulp. Until the cactus falls over and dries out. No new branches will sprout from the fallen branches, as is usually the case, and from the root system nothing new seems to grow as well.

An unknown bug on a Kadushi, in the background the rotting of the plant can be clearly seen.

Observations showed that the ‘wounds’ are often caused by local parakeets, Prikichi, but the rotting process is probably caused by fungi or bacteria. An organism that probably does not belong here, that probably was imported, and that is causing havoc amongst the cacti, the cornerstones of our ecology. Research into the disease and the possible causes of it is necessary, especially since Kadushi is a delicacy on the island (in soups). The cause of the cactus killer might be potentially dangerous to human health. Incidentally, this problem is only found in the Kadushi and not the Datu or Kadushi di Pushi. Leaf cacti are not affected either.

Exotics might kill…

Anyone who looks around a bit and pays attention, will observe the presence of invasive species all around the island. Not all of them are a direct threat to trees and plants of the island. Some threaten wildlife, and of others we have no idea what effect they might have. One thing is certain, though: all invasives have a major impact on the various relationships, connections and processes in nature.

About Michelle da Costa Gomez